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a Nordi G.,Fiskaaling Aquaculture Research Station of the Faroes | Simonsen K.,Fiskaaling Aquaculture Research Station of the Faroes | Danielsen E.,Fiskaaling Aquaculture Research Station of the Faroes | Eliasen K.,Fiskaaling Aquaculture Research Station of the Faroes | And 5 more authors.
Aquaculture Environment Interactions | Year: 2015

The abundance of planktonic sea lice in the surface waters of the strait of Sundalagid, Faroe Islands was investigated from November 2013 to June 2014. The strait is 38 km long and hosts 6 salmon farms with coordinated farming cycles. The spatial distribution of planktonic sea lice for the entire strait was examined in 2 surveys with different wind and hydrographic conditions. Temporal changes were investigated every 2-3 wk at 3 set stations throughout the study. The spatial distribution of Lepeophtheirus salmonis copepodids was clearly influenced by the actual wind direction, as the copepodids were found where winds pushed surface waters towards the shore. The same spatial pattern was not found for Caligus elongatus copepodids. This might be related to a different vertical migration pattern. The abundance of C. elongatus was seasonal. It was the dominant planktonic sea louse during winter, with a mean abundance of 0.34 ± 0.13 ind. m-3, and was virtually absent during summer. Lepeophtheirus salmonis was present throughout the study, except during the last survey when the coordinated farming sites lay fallow. During winter when the warmest seawater was deep in the water column, L. salmonis copepodids were present in 47% of the samples and nauplii were only observed in 9%. In samples where the highest seawater temperature was at the surface, nauplii prevalence attained a high value of 53%, while copepodid prevalence increased to 60%. These results indicate that nauplii might actively seek the highest possible seawater temperature. © The authors 2015. Source

Winthereig-Rasmussen H.,Fiskaaling Aquaculture Research Station of the Faroes | Simonsen K.,Fiskaaling Aquaculture Research Station of the Faroes | Patursson O.,Fiskaaling Aquaculture Research Station of the Faroes
Ocean Engineering | Year: 2016

Computational fluid dynamics (CFD) simulations were performed on the flow through and around full-scale sea cages. The Reynolds average Navier–Stokes equations were solved using a finite volume approach. The realizable k−ϵ model was used to describe turbulence and porous media to represent the flow resistance effect of the net. Velocity deficit was investigated for a single cage, a row of five cages, and two rows of five cages, corresponding to the salmon farm at Gulin in the Faroe Islands. CFD simulations were compared with field measurement data from this farm. The comparison showed that the flow was overpredicted with up to 50% by the CFD simulations using a net solidity corresponding to the net specifications. A hypothesis is presented for the discrepancy between CFD simulations and field measurements, which includes net deformation and fish behavior. Using different cage layouts, different distances between cage centres, and different net soldities, the effects on flow through and around sea cages were examined and discussed. © 2016 Elsevier Ltd Source

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